Fatal error: Uncaught Error: Class "Drupal\Tests\UnitTestCase" not found in /home/fnbrshareacopy/public_html/modules/contrib/select2/tests/src/Unit/Element/Select2Test.php:21 Stack trace: #0 {main} thrown in /home/fnbrshareacopy/public_html/modules/contrib/select2/tests/src/Unit/Element/Select2Test.php on line 21